/Engine/Plugins/Animation/RigLogic/Source/RigLogicLib/Public/dna/layers/DefinitionWriter.h
These indices can be used to access blend shape channel names throughDefinitionReader::getBlendShapeChannelName.
void setBlendShapeChannelIndices ( std::uint16_t index, const std::uint16_t * blendShapeChannelIndices, std::uint16_t count )